1. Field of the Invention
The present invention concerns a water-disintegratable cleaning sheet easily dispersible by water streams. More specifically, it relates to a water-disintegratable cleaning sheet having excellent water disintegratability, wet strength and stability.
2. Related Art Statement
Cleaning sheets are used for wiping human skins such as of hips or for cleaning toilet articles. The cleaning sheets are preferably water-disintegratable so that they can be thrown away to toilets after use. When they are thrown away into a toilet, it would take much time to disperse them in a septic tank unless they are satisfactorily water-disintegratable, and they sometimes clog drainages of the toilet.
Disposable cleaning sheets to be used for wiping are usually marketed while being packaged in a state previously wetted with liquid cleaning medicals in view of convenience and handlability. However, such cleaning sheets must have wet strength sufficient to endure wiping in a state impregnated with liquid cleaning medicals, and are required to be water-disintegratable when thrown away to toilets.
Japanese Patent Publication Hei 7-24636, for example, discloses a water-disintegratable cleaning article comprising a water soluble binder having carboxyl groups, metal ions and an organic solvent. However, the metal ions and the organic solvent are stimulative to skins.
Japanese Patent Laid-Open Hei 3-292924 discloses a water-disintegratable cleaning article comprising fibers containing polyvinyl alcohol and impregnated with an aqueous boric acid solution, and Japanese Patent Laid-Open Hei 6-198778 discloses a water-disintegratable napkin comprising a polyvinylalcohol-containing non-woven fabric incorporated with borate ions and bicarbonate ions. However, polyvinyl alcohol is sensitive to heat, and the wet strength of water-disintegratable articles and water-disintegratable napkins is lowered at 40.degree. C. or higher.
In addition, Japanese Patent Laid-Open Hei 9-170193 discloses a water-disintegratable sheet coated with a water soluble cellulose ether and incorporated with an electrolyte. However, fibrous sheets having more excellent water disintegratability and wet strength have been required.
An object of the present invention is to provide a cleaning sheet having satisfactory water disintegratability, as well as having wet strength so as to be endurable during use in a wet state.
Another object of the present invention is to provide a cleaning sheet of excellent stability not suffering from deterioration of water disintegratability and wet strength even when stored for long time at high temperature in a wet state.